This document discusses different types of hydraulic turbines used to convert potential energy of water into mechanical work. It describes three main types: Pelton wheel (impulse turbine), Kaplan turbine (axial flow propeller turbine), and Francis turbine (mixed flow reaction turbine). The Pelton wheel uses high head water and has a single wheel with buckets that the high-speed water jet hits to rotate the wheel. The Kaplan turbine is for lower heads and resembles a ship propeller. The Francis turbine operates under medium heads and has many curved runner vanes that guide the mixed radial and axial water flow.